In liquid flow systems, when the liquid flows through relatively restricted passages, as is common in flow through a valve, cavitation may result. Cavitation can cause excessive noise, and even damage to the valve and downstream piping. The Vena Contracta, or region of minimum flow stream area, can only occur at or downstream of the point of minimum passage area. As a result, cavitation often takes place at the most sensitive area of a valve, i.e. in the area where relatively soft, or machine finished, sealing surfaces are situated in the flow restricting portion of the valve.